The blading of turbomachines with blade shrouds is sufficiently known from the prior art. Blade shrouds are used on the one hand to mechanically couple the blade tip regions of adjacent blades to one another, thereby resulting in greater rigidity of the blade combination and thus in a higher natural vibration frequency. In addition, sealing bands in turbomachine blading also serve to reduce leakages at the blade tips. To this end, the shrouds also can carry sealing strips which interact with an opposed running surface and form together with the latter a non-contact seal, for example a labyrinth seal. The opposed running surface is often a “honeycomb structure” or another system that tolerates grazing.
The blade shrouds encircling at the circumference can include individual segments which are each integrally cast on the tip of a blade. In running blading, the arrangement of the shroud element results in increased loading of the blade root and of the airfoil on account of the centrifugal forces of the shroud element. Furthermore, the shroud elements need not be mounted centrally at the airfoil tip. This results in an additional bending load for the airfoil and in “tilting”, that is to say lifting on one side, of the shroud element. Furthermore, it has been found that, even with balanced shroud elements, plastic deformations and thus “tilting” may occur in certain regions on account of the centrifugal force. In particular on account of this deformation, gaps may be produced between shroud elements, via which gaps hot gas is able to penetrate into the region above the shroud element. The centrifugal load, in particular in combination with the additional thermal loading, may result in plastic creep deformation. The elastic and plastic asymmetrical deformations referred to may result in a lack of sealing of the sealing gap and/or in excessive grazing of the sealing strips on the opposed running surface.